Lightroom 6 Will Not Open

Which Lightroom version do you have installed. Please check if it's the latest available version 6.14

You can download the installer application file for v6.14 here.- Lightroom 6 End of Support 

I'll recommend saving the installation file for further usage. Because it isn't sure how long this download will be available.

Please check also if there an .lock file besides youe catalog file.

The Lightroom catalog cannot be opened because another application already has it opened - lrcat.lock (adobe.com)

Another step is to try to reset the Lightroom preferences.

https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

It's recommended to backup your preferences before you reset the preferences to the default settings:

https://helpx.adobe.com/lightroom-classic/kb/preference-file-and-other-file-locations.html

Every time you allow a Windows update you run the risk of problems

Do not count on Windows to be fully up to date when it comes to device drivers
Go to the vendor site to be sure you have an updated driver for your graphic adapter

nVidia Driver Downloads https://www.nvidia.com/Download/index.aspx?lang=en-us
-for all Adobe programs use the STUDIO driver, not the GAMING driver
-To achieve the highest level of reliability, Studio Drivers undergo extensive
-testing against multi-app creator workflows and multiple revisions of the top
-creative applications from Adobe to Autodesk and beyond

If you have a laptop you MAY also need to check for a laptop specific nVidia driver
-SOME laptops require an approved driver from the laptop company, not nVidia

AMD/ATI Driver https://www.amd.com/en/support

Intel https://downloadcenter.intel.com/product/211969/Intel-HD-Graphics-Family

Two ideas that MAY work to install and/or run old programs in Windows 10 or Windows 11
-RIGHT click the program icon or EXE and select a compatibility mode in the pop up option window
-and/or select Run as Administrator to assign FULL Windows permissions
-also https://helpx.adobe.com/x-productkb/global/create-local-administrator-account-windows.html